From this, you can extrapolate that stronger channelers will live longer, and look younger for a longer time. But only up to a point, so Rand isn't going to slow at 1/100th the rate of Morghase. And once you look and feel about 65 (which comes after more years of life for stronger channgelers), you're a ticking time bomb. You'll not look or feel older, but some day soon, you'll die.

People like Sorelia and the toothless Wilder Cadsuane meets are products of this Age, where decent healthcare and controlled environments for human habitation are absent. In the AoL, they would all have looked 65. Had Cadsuane not been bound, she would now look around 30 years old (extrapolating from Moghedien), whereas Sorelia looks a lot older even though she's probably the same age.

As for Elaida, obviously her strength in the Power played a role in her becoming advisor to Morghase. Her cozying up to Morghase had just been a way to get added credentials for the job. When the post became open, her relationship with Morghase, added to her strength in the Power meant that when the matter came before the Hall, the Reds could make the proposal and expect support for it. Its like Siuan's administrative skills and her being raised Amyrlin. Obviously it played a role, but since Aes Sedai think strength in the OP goes with strength in character, they wouldn't have considered her for the job at all but for her strength.

Sure, there are Grey sisters we've seen who're not the strongest, but get appointed to top spots. But those are women who have a lot of experience proving that they're good despite their "deficiency" in the Power. Elaida had none of that. Her strength and her relationship with Morghase was all she had.